Welcome Guest [Log In] [Register]
Posted ImageWelcome to the all new Geo Metro Forum. We hope you enjoy your visit.

You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are features you can't use and images you can't see. Registration is simple, fast, and completely free. If you're already a member please log in to your account to access all of our features:

Join our community!




Username:   Password:
Add Reply
Ignition timing question; Have I been timing it wrong?
Topic Started: Feb 26 2012, 03:10 PM (1,202 Views)
Stiffchezze
Member Avatar
Sir Metrologist

So a little background and then on to the questions: :type
I has helping a buddy of mine strip out an old boat that was headed to the "great boatyard in the sky" :'( When I noticed that the gas tank still had some fluid in it. I ran it though my filter that removes all water and debris and lo and behold ~10 gallons of free gas! :banana I shudder to think of how old it is, but it still burns and at $3.50 a gallon I'm WAY too cheap to not use $35 of free gas. So long story short I mix it in about a gallon at a time in the Metro and off I go. :drivin No problems until this last tank; I got a little greedy. I mixed in TWO gallons this time, and understandable I started to get a bit of ping. :smackface I normally run Rudolph at 10-11 BTC with no problems, but it is a little high for REALLY old gas.

So last night I decide to back the timing down until I can burn off this tank. I get Rudolph up to temp, hook up my timing light, connect the "jumper wire" at the diagnostic connector and check my current timing. I have set timing by ear many a time, but I'm a big beliver that If you have the tool, why not use it? ^o)
It was right were I left it at ~10.5 BTC. For "grins" I activated my Bluetooth scanner and watched the timing as reported by the ECU.
Link--->OBDII ELM327 Bluetooth Connector
I noticed that the timing was still jumping around a bit between 6-10 BTC whether the jumper was attached or not. It *should* have shone 5 BTC with the jumper on, as this is base timing for my Metro, and my understanding is that the jumped wire is suppose to lock the timing back to base in the ECU so that you can set the distributor to match. (or were YOU want it at :evillol )

I just ignored it, and set the timing the way I always do to 7 BTC. After I was done, I closed it up and went to bed. This morning the wife and I got up and decided to go to breakfast. We took the Metro, and about a mile down the road, the CEL popped on. A quick scan in route (I LOVE that scanner! :wub: ) told me P1530 – Manufacture Specific Code. A quick scan of the forum and:
Quote:
 
P1530 - Ignition Timing Adjustment Switch Circuit Malfunction

I figured it was left over from last night. I cleared it, (also in route :wub: ) and the wife and I had a nice meal. On the trip home, the light popped back on and that’s when I realized I forgot to pull the "jumper wire" last night. :smackface
At the house, I checked ignition timing in the ECU before I pulled the wire and it showed it was locked at 5 BTC!!! :O :hmm I left the Metro idling and hooked up the timing light and it showed 10 BTC dead on. I adjusted the timing back to 7 BTC and the mark on the crank was more steady than I've ever seen it.
This (finally :P ) brings me to my questions:

I always thought that when you "jumped" the connector, it locked the timing down in the ECU, but it seems like that doesn't happen until it throws the code. Is this always the case? Is it just the case with my Metro? Have I been timing it wrong? Have we all been timing it wrong? Does anyone else have a scanner to check ignition timing with the jumper connected and disconnected, and with the code thrown? It only takes about two to three miles with the jumper connected to throw the code. Anybody? :banghead
Offline Profile Quote Post Goto Top
 
Bad Bent
Member Avatar
Facetious Educated Donkey

Stiffchezze
Feb 26 2012, 03:10 PM
I always thought that when you "jumped" the connector, it locked the timing down in the ECU, but it seems like that doesn't happen until it throws the code. Is this always the case? Is it just the case with my Metro? Have I been timing it wrong? Have we all been timing it wrong? Does anyone else have a scanner to check ignition timing with the jumper connected and disconnected, and with the code thrown? It only takes about two to three miles with the jumper connected to throw the code. Anybody? :banghead
As anybody....

No, we have not been timing our Geos incorrectly if we follow the directions, IMHO. What you describe is what my FSM says.

My understand is that when we jumper the ECU (diagnostic terminals C and D) it prevents the ECM from changing the timing while you adjust the base timing manually. It does not 'lock the timing down in the ECU' per say but more of a lock out.

Assume that after you make a change and disconnect the jumper then the ECU will have a fit controlling the timing until it regains control of it's sensors. Control freak. :lol

If, as in your case and mine, if you leave the jumper in they yes; I assume it would go to go to "save mode" and lock the timing at 5o to prevent any damage, as you found out.
Offline Profile Quote Post Goto Top
 
Stiffchezze
Member Avatar
Sir Metrologist

This is why two heads are better than one... ^o)

Quote:
 
My understand is that when we jumper the ECU (diagnostic terminals C and D) it prevents the ECM from changing the timing while you adjust the base timing manually. It does not 'lock the timing down in the ECU' per say but more of a lock out.


This makes sense, however why does the ECU continue to report that the timing still changes even with the jumper installed? Its only a degree or two, and without a scanner reporting live data, you would never see it, but it does change. That is unless the code is thrown. :ermm:

Quote:
 
If, as in your case and mine, if you leave the jumper in they yes; I assume it would go to go to "save mode" and lock the timing at 5o to prevent any damage, as you found out.

This also makes complete sense. However after the code was thrown, my manual base timing was off by ~2o . Even if the ECU timing was locked at 5o shouldn't the base timing stay the same no mater what? :hmm

I know this is kinda trivial, I'm just trying to wrap my head around this one and appreciate the help. :thumb
Offline Profile Quote Post Goto Top
 
Bigshane90


I had my timing change on my 1.3 and I still do not know why.
I installed my new cam,timing belt. Set timing to 10*. It ran like a raped ape, for about a week or two. Then it started missing, smelling of raw gas out the exhaust and wouldn't drive over a rock in the road. I pulled it back in and pointed the light at it. It was now retarded 5*? The distributor bolts were still tight. So I re set the timing again to 10*, it didn't run as good as the first week.
So I tore the timing cover back off and the belt was perfect and had not jumped a tooth.
The car used to sqeak the tires when I stomped it, not anymore. And i don't have a clue what happened.
Offline Profile Quote Post Goto Top
 
Rooy


Bigshane90
Feb 27 2012, 11:21 PM
I had my timing change on my 1.3 and I still do not know why.
I installed my new cam,timing belt. Set timing to 10*. It ran like a raped ape, for about a week or two. Then it started missing, smelling of raw gas out the exhaust and wouldn't drive over a rock in the road. I pulled it back in and pointed the light at it. It was now retarded 5*? The distributor bolts were still tight. So I re set the timing again to 10*, it didn't run as good as the first week.
So I tore the timing cover back off and the belt was perfect and had not jumped a tooth.
The car used to sqeak the tires when I stomped it, not anymore. And i don't have a clue what happened.
Crank gear woodruff key sheared?
Offline Profile Quote Post Goto Top
 
Bad Bent
Member Avatar
Facetious Educated Donkey

Stiffchezze
Feb 27 2012, 10:54 PM
Quote:
 
If, as in your case and mine, if you leave the jumper in they yes; I assume it would go to go to "save mode" and lock the timing at 5o to prevent any damage, as you found out.

This also makes complete sense. However after the code was thrown, my manual base timing was off by ~2o . Even if the ECU timing was locked at 5o shouldn't the base timing stay the same no mater what? :hmm
Could be as Bigshane90 and Rooy suggest.

Off 2o, that's one mark on a rather cheap piece of plastic.

If it's steady at that setting then first I'd think I forgot what I set it as last time. :smackface
Or Parallax error: that I was not looking at it at the scale at the same angle I was looking at it before. Parallax error is quite common when looking at gauges. Only a mirrored surface behind the needle or going digital can eliminate it. Tilting the head or even using one or the other eye can change the angle enough for a bad reading or at least a different one. :-/
Also FYI the accuracy of reading any scale is 1/2 the gradient. From mark to mark the eye can only divide it in half accurately.

That said I'll toss in a stretched timing belt could be a problem
Offline Profile Quote Post Goto Top
 
Bigshane90


Rooy
Feb 27 2012, 11:53 PM
Bigshane90
Feb 27 2012, 11:21 PM
I had my timing change on my 1.3 and I still do not know why.
I installed my new cam,timing belt. Set timing to 10*. It ran like a raped ape, for about a week or two. Then it started missing, smelling of raw gas out the exhaust and wouldn't drive over a rock in the road. I pulled it back in and pointed the light at it. It was now retarded 5*? The distributor bolts were still tight. So I re set the timing again to 10*, it didn't run as good as the first week.
So I tore the timing cover back off and the belt was perfect and had not jumped a tooth.
The car used to sqeak the tires when I stomped it, not anymore. And i don't have a clue what happened.
Crank gear woodruff key sheared?
Would it still run like this? Because I still drive it daily.
Offline Profile Quote Post Goto Top
 
Rooy


If it's only partially sheared it can still run. There are more than a few cases of this happening that have been posted on this forum.
Offline Profile Quote Post Goto Top
 
Bigshane90


I guess ill have to check this out.
Thanks.
Offline Profile Quote Post Goto Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
DealsFor.me - The best sales, coupons, and discounts for you
« Previous Topic · Engine Tech & Diagnostics · Next Topic »
Add Reply